Substations in high and medium-voltage power networks include primary devices, such as electrical cables, lines, bus bars, switches, power transformers and instrument transformers, which can be arranged in switch yards and/or bays. These primary devices can be operated in an automated way via a Substation Automation (SA) system. The SA system includes secondary devices, among which Intelligent Electronic Devices (IED) can be responsible for protection, control and monitoring of the primary devices. The secondary devices can be hierarchically assigned to a station level or a bay level of the SA system. The station level can include a supervisory computer including an Operator Work Station (OWS) with a Human-Machine Interface (HMI) and running a station-level Supervisory Control And Data Acquisition (SCADA) software, as well as a gateway that communicates the state of the substation to a Network Control Centre (NCC) and receives commands from it. IEDs on the bay level, also termed bay units, in turn can be connected to each other as well as to the IEDs on the station level via an inter-bay or station bus that can exchange commands and status information.
A communication standard for communication between the secondary devices of a substation has been introduced by the International Electrotechnical Committee (IEC) as part of the standard IEC 61850 entitled “Communication Networks and Systems in Substations.” For non-time critical report messages, section IEC 61850-8-1 specifies the Manufacturing Message Specification (MMS, ISO/IEC 9506) protocol based on a reduced Open Systems Interconnection (OSI) protocol stack with the Transmission Control Protocol (TCP) and Internet Protocol (IP) in the transport and network layer, respectively, and Ethernet and/or RS-232C as physical media. For time-critical event-based messages, such as trip commands, IEC 61850-8-1 specifies the Generic Object Oriented Substation Events (GOOSE) directly on the Ethernet link layer of the communication stack. For fast periodically changing signals at the process level, such as measured analogue voltages or currents, section IEC 61850-9-2 can specify the Sampled Value (SV) service, which like GOOSE builds directly on the Ethernet link layer.
SA systems based on IEC61850 can be configured by a standardized configuration representation or formal system description called Substation Configuration Description (SCD). An SCD file can include the logical data flow between the IEDs on a “per message” base, for example, for every message source, a list of destination or receiver IEDs, the message size in terms of data set definitions, as well as the message sending rates for all periodic traffic like reports, GOOSE, and SV.
Substation Automation (SA) systems can include a number of basic SA functions for protection, control and monitoring of the substation. These functions can relate to individual pieces of primary equipment or to entire substation bays. In addition, higher-level applications can be provided, which involve at least a station level operator HMI and/or the connection to a remote operation place or network control center by a gateway. Applications can be used as operator support or for automating handling of emergency situations within the station. They can involve operational information from more than one piece of primary equipment, even from more than one bay, and hence are termed “inter-bay”, “station-level”, or “distributed.” In addition to a possible primary functional or operational goal, a configuration of such inter-bay applications therefore can also rely on the dynamic switchyard configuration or topology, as well as the basic SA functions used to gather data from the switchyard and execute commands on it. Inter-bay functions can be station-level interlocking, station and bay level switching sequences, transformer parallel control, transformer auto close functions and load shedding.
Inter-bay functions can be engineered or implemented on top of an existing SA system. The latter can provide the process state information and some means to control the process. This engineering can be done manually, by instantiating the needed function blocks and connecting them signal-wise to the existing SA system. For some station-level functions, for example switching sequences, even a complete new IED may be used, including dedicated, and hence at least partly duplicated, wiring or cabling to the switch yard.
According to the patent application EP-A 1191662, an engineering wizard for an SA function can automatically generate the data flow between IEDs and a function configuration, based on known switchgear parameter values and function block allocation to the switchgear as obtained from a Substation Configuration Description. For example, the configuration of a first SA function can involve allocating this function to a primary device and an IED. Following this, a primary device model and a topology model can be used to automatically determine second, more basic, SA functions, of which data or procedures are used by the first SA function during operation. If desired, the corresponding communication links between the first SA function and the second SA functions can be determined automatically on the basis of a communication model.
According to the U.S. Pat. No. 4,767,941, the implementation of interlocking functionality can be automated based on an actual topology of the substation, for example the actual switching states of all switching devices, and based on an exhaustive set of rules for interlocking operation. Decoupling the topological configuration of the substation from the interlocking rules can allow updating each of them independently and thus can increase flexibility. The signals that indicate the switching state of the associated switching devices can be supplied via dedicated data buses and data links to a centralized data acquisition and processing unit. By evaluating the signals the actual topology of the substation can be inferred, and based on the interlocking rules, a release pattern can be determined and stored. The latter indicates a release or blocking property for each switching device, for example if a specific switching operation request command is to be accepted or refused.
In the context of the present disclosure, an inter-bay SA application can be understood to involve and coordinate substation primary devices arranged in a plurality of substation bays and defining a coordination range corresponding to a particular voltage level within a substation, a single substation, or a plurality of substations.